S&P on Friday downgraded 9 of 17 euro zone member, among them Slovenia, saying policy makers have not done enough to address the euro zone debt crisis.

Slovenia's rating fell by one notch to A+ from AA- and carries a negative outlook.

"Slovenia is enforcing all acts necessary to stabilize public finances although the country is forming a new government," Finance Ministry said in a statement.

"The rating cut is excessive in our view and does not take into account all decress taken so far by the European Union and Slovenia," it added, citing budget savings made in 2011 and planned for 2012.

It said the central government budget deficit last year reached 4.3 percent of GDP and was 0.4 percent lower than planned earlier, adding Slovenia was sticking to its plan to reduce the general budget deficit to below 3 percent of GDP -- which is the maximum level allowed for euro zone members -- by the end of 2013.

Slovenia was badly hit by the global crisis due to its dependency on exports and its economy contracted by 8 percent in 2009.

A mild recovery followed in 2010 but latest figures show another recession is possible as the economy contracted by 0.5 percent in the third quarter of 2011.

The centre-left government of the outgoing Prime Minister Borut Pahor was ousted by parliament in September over internal coalition squabbles and its inability to implement reforms that would speed up economic growth.

A snap election was held on December 4 but the centre-left ex-Ljubljana mayor Zoran Jankovic, whose Positive Slovenia party gained most votes, was on Wednesday rejected by parliament as a prime minister.

President and parliamentary parties have to nominate new candidates for the prime minister over the next 11 days, with Janez Jansa, head of the centre-right Slovenian Democratic Party, the second largest party in parliament, being the most likely candidate.

The other two major ratings agencies have also lowered Slovenia's rating since September amid the political crisis, lack of reforms and the deepening of the euro zone debt crisis. Fitch rates Slovenia at AA- and Moody's at A1.

(Reporting By Marja Novak, Editing by Jonathan Thatcher)